Mithral is one of several magical metals from the settings of Dungeons & Dragons, and is one of the two most iconic, after Adamantine. Characterized by its beautiful bright silvery color, mithral is notable for having high durability whilst being lightweight; weapons made from mithral may not have the innate cutting power of adamantine weapons, but armor made from mithral is exceedingly light and easy to move in, whilst still offering better protection than anything made of steel.
Mithral originates from the writings of J.R.R. Tolkien, who envisioned this ultra-durable, silver-like metal as the most precious and valuable ore on Middle-Earth. He spelled his version as Mithril, whilst D&D changed the i to an a in order to avoid copyright. Still, the two names sound so alike that they are generally used interchangeably, especially as their effects are identical.